Baffling and gas-distributing structures are commonly used when it is necessary to disperse a gas stream over the entire cross section of a passage to which the gas is to be fed.
Particularly in gas-processing apparatus, such as electrostatic precipitators, it is necessary to feed the gas from a duct of relatively small cross section to a chamber or inlet of much larger cross section.
When the gas stream is to be uniformly distributed in such a system, the common technique is to provide a diffuser structure as a transition member between the gas duct and the processing apparatus, namely the electrostatic reciprocator. Such a diffuser provides a progressively increasing flow cross section.
Experience has shown that the uniform distribution of a gas stream in a progressively increasing cross section requires a distributing or baffling structure for redirection or establishment of flow lines when the angle of divergence exceeds a predetermined lower limit.
Expressly pronounced divergences are present in the feed devices to electrostatic precipitators and one can encounter an increase in the cross section of 15 times. It has been found to be necessary to provide distributors of this type with internal structures having the functions indicated.
Such gas-distributing structures generally consist of perforated panels, e.g. sheet metal walls punched with apertures, windows or openings, so that there is a certain ratio of opening cross section to baffle area. These panels are disposed at right angles to the gas flow and, where the cross section is large, each panel may be made up of plurality of contiguous plates secured by connectors to a carrying or support structure. The entire assembly is generally planar or flat and a plurality of such assemblies may be provided in spaced-apart relation.
The assemblies are generally oriented vertically with the support members also running vertically and the contiguous edges of the plates running horizontally.
The most common construction of such assemblies makes use of a bolted connection between the plates and the support members which are generally L-section structural shapes. Assembly at the site restricts the size of the profiled plate which can be used, as well as the weight thereof, and hence a large number of profiled plates and a correspondingly large number of connecting elements are required for large-cross section gas-distributing assemblies.
The assembly at the site is also expensive and time consuming, because each plate must be affixed to the adjacent plate and/or the support structures or framing elements at a plurality of locations each of which has a plurality of bolts. Efforts to prefabricate such structures and to minimize the number of strips required for on-site erection of the units have proved to be fruitless.